Recharging system of hybrid vehicle using neutral points of two motors

ABSTRACT

A system for recharging a hybrid vehicle is provided with two motors and supplies commercial electricity to neutral points of the motors when a connection of a recharging stand is detected, forms an electricity loop through the neutral points of the first motor and the second motor according to a phase of the commercial electricity, and carries out a recharging mode by detecting at least a voltage of a DC link capacitor in a voltage converter, a voltage of a smoothing capacitor, and a battery voltage. According to the system, a current control value or a voltage control value is selected according to the recharging mode in order to recharge a battery based on the current control value or the voltage control value.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationSer. No. 12/958,018 filed Dec. 1, 2010, which claims priority to and thebenefit of Korean Patent Application No. 10-2010-0066377 filed in theKorean Intellectual Property Office on Jul. 9, 2010, the entire contentsof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a hybrid vehicle provided with twomotors. More particularly, the present invention relates to a rechargingsystem of the hybrid vehicle that recharges a battery by using neutralpoints of the two motors.

(b) Description of the Related Art

In order to meet tightened exhaust gas regulations on vehicles and toenhance fuel consumption, hybrid vehicles have been developed.

A hybrid vehicle generates electricity through regenerative braking bywhich a motor rotates inversely in a case of deceleration and rechargesa battery. In addition, hybrid vehicles can enhance fuel consumption andreduce exhaust gases through ISG (Idle Stop and Go) control where anengine is stopped when the vehicle stops, and the engine is restarted byusing the motor when the vehicle begins to run.

In addition, a plug-in recharging method may be applied to hybridvehicles. According to the plug-in recharging method, the battery isrecharged by using exterior commercial electricity.

An on-board charger which rectifies the commercial electricity andrecharges the battery more slowly may be provided so as to apply theplug-in recharging method.

However, use of an on-board charger is undesirable, at least becauseon-board chargers generally are expensive and heavy, thus increasingmanufacturing costs and negatively impacting fuel efficiency of thehybrid vehicle. In addition, since the charger often must be mounted ina limited space, it can be difficult to manufacture the charger as apackage.

Particularly, since the on-board charger may cost about ten times morethan an inverter producing the same output, use of such a charger isundesirable.

In addition, a high-speed recharging device may be provided so as torecharge the battery in a short time. In this case, commercialelectricity is connected to a high-speed recharging port.

Conventionally, a high-speed recharging device must communicate with abattery controller at a high speed in real time so as to preventovercharge of the battery and protect the battery. For this purpose, thehigh-speed recharging device has an additional communication channel.

However, in the event that a communication channel of an exterior systemis connected to controllers in the hybrid vehicle, it may be difficultto assure reliability of the controller.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a recharging system of ahybrid vehicle in which it is possible to recharge a battery by usingmotors and inverters selectively connected to commercial electricitywithout an additional expensive charger.

A recharging system of hybrid vehicle according to first and secondexemplary embodiments of the present invention preferably includes atleast a battery in which DC voltage is stored or for outputting the DCvoltage; first and second motors configured to function as an electricmotor or a generator; first and second inverters for operating the firstand second motors respectively; a voltage converter for raising orlowering the DC voltage of the battery such that the raised or loweredDC voltage is supplied to the first and second inverters, in order toraise or lower the DC voltage supplied from the first and secondinverters such that the raised or lowered DC voltage is supplied to thebattery, and provided with a DC link; first and second diodes eachprovided with an anode terminal connected to a negative terminal of thefirst and second inverters and a cathode terminal connected to a sourceof commercial electricity and connected in parallel to first and secondneutral points of the first and second motors; and a rechargingcontroller for carrying out a recharging mode by detecting at least oneof a phase of the commercial electricity supplied to the first andsecond neutral points of the first and second motors, a voltage of a DClink capacitor connecting the voltage converter and the first and secondinverters, a battery voltage, a voltage of a smoothing capacitorconnected at both terminals of the battery, a battery current, and acurrent flowing from the voltage converter to the battery, andcontrolling the voltage converter through a PWM duty according to therecharging mode of the battery such that the voltage of the DC linkcapacitor is raised or lowered and is supplied to the battery.

The recharging controller may decide a current control value and maycontrol a charging current of the battery to follow the current controlvalue in a case that the recharging mode of the battery is a currentcontrol mode.

The recharging controller may decide a voltage control value requiredfor maintaining the voltage of the smoothing capacitor to be constantand may control the voltage converter based on the voltage control valueso as to recharge the battery in a case that the recharging mode of thebattery is not the current control mode.

According to the second exemplary embodiment of the present invention,the recharging system may further include: a main relay selectivelyconnecting the battery with the voltage converter; a recharging portselectively connecting the commercial electricity disposed at anexterior of the vehicle to the first and second diodes; and a connectiondetector for detecting a connection of the commercial electricity.

The recharging controller may perform an initial activation thereof andmay switch on the main relay so as to pre-recharge the DC link by meansof the battery voltage in a case that the connection detector detectsthe connection of the commercial electricity.

The recharging controller may control a recharge of the batteryaccording to the recharging mode in a case that the pre-recharge of theDC link is completed.

The recharging controller may decide the current control value andcontrols the charging current of the battery to follow the currentcontrol value in a case that the recharging mode of the battery is thecurrent control mode.

The recharging controller may decide a voltage control value requiredfor maintaining the voltage of the smoothing capacitor to be constantand may control the voltage converter based on the voltage control valueso as to recharge the battery in a case that the recharging mode of thebattery is not the current control mode.

The recharging controller may discharge the voltage of the DC linkcapacitor to be lower than a reference voltage to the battery in a casethat a disconnection of the commercial electricity is detected duringrecharge or after the recharge is completed.

A recharging system of a hybrid vehicle according to third and fourthexemplary embodiments of the present invention may include: a battery inwhich DC voltage is stored or outputting the DC voltage; first andsecond motors configured to function as an electric motor or agenerator; first and second inverters for operating the first and secondmotors respectively; a voltage converter for raising or lowering the DCvoltage of the battery such that the raised or lowered DC voltage issupplied to the first and second inverters, in order to raise or lowerthe DC voltage supplied from the first and second inverters such thatthe raised or lowered DC voltage is supplied to the battery, andprovided with a DC link; first and second diodes each provided with ananode terminal connected to a negative terminal of the first and secondinverters and a cathode terminal connected to a source of commercialelectricity and connected in parallel to first and second neutral pointsof the first and second motors; a recharging controller for carrying outa recharging mode by detecting at least one of a phase of the commercialelectricity supplied to the first and second neutral points of the firstand second motors, a voltage of a DC link capacitor connecting thevoltage converter and the first and second inverters, a battery voltage,a voltage of a smoothing capacitor connected at both terminals of thebattery, a battery current, and a current flowing from the voltageconverter to the battery, and controlling the voltage converter througha PWM duty according to the recharging mode of the battery such that thevoltage of the DC link capacitor is raised or lowered and is supplied tothe battery; a main relay selectively connecting the battery with thevoltage converter; a recharging port selectively connecting thecommercial electricity disposed at an exterior of the vehicle to thefirst and second diodes; a connection detector for detecting aconnection of the commercial electricity; and an input terminal switchmounted between the recharging port and the first and second motors andselectively connecting the commercial electricity to the first andsecond neutral points of the first and second motors by a control of therecharging controller.

According to the third exemplary embodiment of the present invention,the input terminal switch may include: a first relay connected to thefirst diode and the first neutral point of the first motor; and a secondrelay connected to the second diode and the second neutral point of thesecond motor.

The recharging controller may perform an initial activation thereof, mayswitch on the main relay, and may switch off the input terminal switchso as to pre-recharge the DC link by means of the battery voltage in acase that the connection detector detects the connection of thecommercial electricity.

The recharging controller may switch on the input terminal switch andmay control a recharge of the battery according to the recharging modein a case that the pre-recharge of the DC link is completed.

The recharging controller may decide the current control value and maycontrol the charging current of the battery to follow the currentcontrol value in a case that the recharging mode of the battery is thecurrent control mode.

The recharging controller may decide a voltage control value requiredfor maintaining the voltage of the smoothing capacitor to be constantand may control the voltage converter based on the voltage control valueso as to recharge the battery in a case that the recharging mode of thebattery is not the current control mode.

According to the fourth exemplary embodiment of the present invention,the input terminal switch may include: a first relay connected to thefirst diode and the first neutral point of the first motor; a secondrelay connected to the second diode and the second neutral point of thesecond motor; and a third relay connected in parallel with the firstrelay and connected in series with a resistance.

The recharging controller may perform an initial activation thereof, mayswitch on the second and third relays of the input terminal switch so asto form a low current loop, and may pre-recharge the DC link by using anelectricity of the low current loop in a case that the connectiondetector detects the connection of the commercial electricity.

The recharging controller may switch off the third relay, may switch onthe first relay, and may switch on the main relay so as to recharge thebattery by using the normal commercial electricity in a case that thepre-recharge of the DC link is completed.

The recharging controller may discharge the voltage of the DC linkcapacitor to be lower than a reference voltage to the battery in a casethat a disconnection of the commercial electricity is detected duringrecharge or after the recharge is completed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a recharging system of a hybrid vehicleaccording to a first exemplary embodiment of the present invention.

FIG. 2 is a flowchart showing a method for recharging a battery by usingthe recharging system of FIG. 1.

FIGS. 3 and 4 are circuit diagrams showing current flow according to aphase of commercial electricity in a recharging system according to thefirst exemplary embodiment of the present invention.

FIG. 5 is a circuit diagram of a recharging system of a hybrid vehicleaccording to a second exemplary embodiment of the present invention.

FIGS. 6A and 6B are flowcharts of a method for recharging a battery byusing the recharging system of FIG. 5.

FIG. 7 is a flowchart of a method for pre-recharging a DC link by usinga recharging system according to the second exemplary embodiment of thepresent invention.

FIG. 8 is a circuit diagram of a recharging system of a hybrid vehicleaccording to a third exemplary embodiment of the present invention.

FIG. 9 is a flowchart of a method for pre-recharging a DC link by usingthe recharging system of FIG. 8.

FIG. 10 is a flowchart of a method for recharging a battery by using arecharging system according to the third exemplary embodiment of thepresent invention.

FIG. 11 is a flowchart of a method for completing a recharge of abattery by using a recharging system according to the third exemplaryembodiment of the present invention.

FIG. 12 is a circuit diagram of a recharging system of a hybrid vehicleaccording to a fourth exemplary embodiment of the present invention.

FIG. 13 is a flowchart of a method for pre-recharging a DC link by usingthe recharging system of FIG. 12.

FIG. 14 is a flowchart of a method for recharging a battery by using arecharging system according to the fourth exemplary embodiment of thepresent invention.

FIG. 15 is a flowchart of a method for completing a recharge of abattery by using a recharging system according to the fourth exemplaryembodiment of the present invention.

DESCRIPTION OF SYMBOLS

101: the first motor 102: the second motor 103: the first inverter 104:the second inverter 105: voltage converter 106: battery 107: diode 108:recharging port 109: connection detector 110: input terminal switch

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Exemplary Embodiment

Hereinafter, a first exemplary embodiment of the present invention willbe described in detail referring to the drawings.

As those skilled in the art would realize, the described embodiments maybe modified in various different ways, all without departing from thespirit or scope of the present invention. Description of components thatare not necessary for explaining the present invention will be omitted,and the same constituent elements are denoted by the same referencenumerals in this specification.

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g. fuels derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example bothgasoline-powered and electric-powered vehicles.

FIG. 1 is a circuit diagram of a recharging system of a hybrid vehicleaccording to the first exemplary embodiment of the present invention.

Referring to FIG. 1, the first exemplary embodiment of the presentinvention preferably includes at least a first motor 101, a second motor102, a first inverter 103, a second inverter 104, a voltage converter105, a battery 106, a diode 107 (for example, including first and seconddiodes D1 and D2), and a recharging controller 200.

The first motor 101 is a 3-phase AC electric motor, which can beoperated as an electric motor to start an engine (not shown), andselectively operated as a generator driven by the engine.

The first motor 101 preferably is powered by 3-phase AC voltage suppliedthrough the first inverter 103 so as to start the engine. In addition,the first motor 101 configured to be driven by the engine so as togenerate 3-phase AC voltage and output the 3-phase AC voltage to thefirst inverter 103.

The second motor 102 is a 3-phase AC electric motor capable of driving adriving wheel (not shown) and generating driving torque by 3-phase ACvoltage supplied from the second inverter 104.

In addition, the second motor 102 can be operated as a generator in acase of regenerative braking of the vehicle so as to generate 3-phase ACvoltage and output the 3-phase AC voltage to the second inverter 104.

The first motor 101 can include a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a firstneutral point N1 and the other end connected to a corresponding arm ofthe first inverter 103.

The first neutral point N1 of the first motor 101 is connected tocommercial electricity 300 that preferably is input from the exterior.

The second motor 102 includes a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a secondneutral point N2 and the other end connected to a corresponding arm ofthe second inverter 104.

The second neutral point N2 of the second motor 102 is connected tocommercial electricity 300 that preferably is input from the exterior.

The first inverter 103 converts the DC voltage of the battery 106supplied through the voltage converter 105 into 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the first motor 101 as a drivingvoltage.

The first inverter 103 is connected to a DC link (a portion to which Vdcis applied) of the voltage converter 105 and the second diode D2 of thediode 107 so as to form a circulation path when the commercialelectricity 300 supplied to the first inverter 103 through the firstneutral point N1 of the first motor 101 has a positive value (Vs>0).

The second inverter 104 converts the DC voltage of the battery 106supplied through the voltage converter 105 into 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the second motor 102 as a drivingvoltage.

The second inverter 104 is connected to the DC link of the voltageconverter 105 and the first diode D1 of the diode 107 so as to form acirculation path when the commercial electricity 300 supplied to thesecond inverter 104 through the second neutral point N2 of the secondmotor 102 has a negative value (Vs<0).

The first inverter 103 is formed by connecting electric switchingelements in series, and includes U phase arms Sau and Sau′, V phase armsSay and Say′, and W phase arms Saw and Saw′.

One of an NPN transistor, an IGBT (Insulated Gate Bipolar Transistor),and an MOSFET may be used as the electric switching element.

The second inverter 104 is formed by connecting electric switchingelements in series, and includes U phase arms Sbu and Sbu′, V phase armsSbv and Sbv′, and W phase arms Sbw and Sbw′.

One of an NPN transistor, an IGBT (Insulated Gate Bipolar Transistor),and an MOSFET may be used as the electric switching element.

The voltage converter 105 is a DC/DC converter, and thus raises orlowers the DC voltage supplied from the battery 106 to a voltage ofpredetermined level according to a PWM duty control signal applied fromthe recharging controller 200, and outputs it to the first inverter 103or the second inverter 104.

In addition, the voltage converter 105 raises or lowers the DC voltageapplied from the first inverter 103 or the second inverter 104 accordingto a PWM duty control signal applied from the recharging controller 200and outputs it to the battery 106 as a recharging voltage.

The voltage converter 105 preferably is connected to both ends of thebattery 106, and includes first and second electric switching elementsS1 and S2 connected in series with a DC link capacitor Cdc and asmoothing capacitor Cbc smoothing a voltage change between both ends ofthe battery 106.

In a case that the exterior commercial electricity 300 supplied to thefirst neutral point N1 of the first motor 101 and the second neutralpoint N2 of the second motor 102 is supplied to the DC link forming thecirculation path through the first inverter 103 and the second inverter104, the voltage converter 105 switches on or off the first electricswitching element S1 and the second electric switching element S2according to a control signal applied from the recharging controller 200and recharges the battery 106.

The battery 106 preferably utilizes DC electricity. For example, one ofnickel-hydrogen and lithium-ion rechargeable battery and a capacitor oflarge capacity may be used as the battery 106. Preferably, the DCvoltage recharged in the voltage converter 105 is raised or lowered soas to be supplied to the first motor 101 or the second motor 102.

In addition, the battery 106 can be recharged by exterior commercialelectricity 300, which is raised or lowered by the voltage converter 105and applied to the battery 106.

The diode 107 includes the first diode D1 and the second diode D2. Oneterminal, e.g., an anode terminal of the diode 107 is connected to anegative terminal of the first and second inverters 103 and 104, and acathode terminal is connected to the exterior commercial electricity 300and the first and second neutral points N1 and N2 of the first andsecond motors 101 and 102.

The commercial electricity 300 can be connected to the system through aplug connection or a connector connection.

The commercial electricity 300 may be AC electricity or DC electricity.

The recharging controller 200 detects a phase Vs of the commercialelectricity 300 supplied to the first neutral point N1 of the firstmotor 101 and the second neutral point N2 of the second motor 102, avoltage Vdc of a DC link capacitor Cdc forming a circulation loop, abattery voltage Vb, a voltage Vbc of the smoothing capacitor Cbcconnected to both ends of the battery 106, an inductor current I_(L),and a charging current Ib and determines a recharging mode.

In addition, the recharging controller 200 decides a recharging controlvalue according to the recharging mode, and recharges the battery 106 byswitching on or off the first electric switching element S1 and thesecond electric switching element S2 of the voltage converter 105through the PWM duty control.

One of ordinary skill in the art would understand that driving the firstmotor by the battery voltage and starting the engine, recharging thebattery by the voltage generated by the driving torque of the engine,driving the second motor by the battery voltage and running the vehicle,and recharging the battery through the regenerative braking as performedin conjunction with the first exemplary embodiment of the presentinvention are the same as those according to conventional arts, anddetailed descriptions thereof will be omitted.

The first exemplary embodiment of the present invention relates torecharging the battery 106 by supplying the exterior commercialelectricity to the first neutral point N1 of the first motor 101 and thesecond neutral point N2 of the second motor 102 without the need foradditional recharging devices, which will be described in further detailherein.

FIG. 2 is a flowchart showing a method for recharging a battery by usinga recharging system according to the first exemplary embodiment of thepresent invention.

Referring to FIG. 2, in a state that the recharging controller 200 ofthe hybrid vehicle according to the first exemplary embodiment of thepresent invention stands by at step S101, it is determined whether thecommercial electricity 300 is connected through the plug connection orthe connector connection at step S102.

If the commercial electricity 300 is connected for recharging thebattery 106, the commercial electricity 300 is supplied to the firstneutral point N1 of the first motor 101 and the second neutral point N2of the second motor 102 at step S103.

At step S104, an electricity loop shown in FIG. 3 is formed if the phaseof the commercial electricity 300 is positive value (Vs>0), and theelectricity loop shown in FIG. 4 is formed if the phase of thecommercial electricity 300 is a negative value (Vs<0). Therefore, the DClink capacitor Cdc included in the voltage converter 105 is recharged.

Referring to FIG. 3, the electricity loop in a state that the phase ofthe commercial electricity 300 is a positive value (Vs>0) is formed asfollows.

The voltage of the commercial electricity 300 is supplied to the firstneutral point N1 of the first motor 101, and an upper U phase arm Sau,an upper V phase arm Say, and an upper W phase arm Saw of the electricswitching element constituting the first inverter 103 is electrified. Atthis time, each upper arm may be electrified through a bypass diodeconnected in parallel therewith.

Therefore, a current of the commercial electricity 300 flows to the DClink capacitor Cdc in the voltage converter 105 through the upper Uphase arm Sau, the upper V phase arm Say, and the upper W phase arm Sawof the first inverter 103, and is returned to the commercial electricity300 through the second diode D2 of the diode 107 connected to thenegative terminal of the first and second inverters 103 and 104.

Referring to FIG. 4, the electricity loop in a state that the phase ofthe commercial electricity 300 is negative value (Vs<0) is formed asfollows.

The voltage of the commercial electricity 300 is supplied to the secondneutral point N2 of the second motor 102, and an upper U phase arm Sbu,an upper V phase arm Sbv, and an upper W phase arm Sbw of the electricswitching element constituting the second inverter 104 is electrified.At this time, each upper arm may be electrified through a bypass diodeconnected in parallel therewith.

Therefore, the current of the commercial electricity 300 flows to the DClink capacitor Cdc in the voltage converter 105 through the upper Uphase arm Sbu, the upper V phase arm Sbv, and the upper W phase arm Sbwof the second inverter 104, and is returned to the commercialelectricity 300 through the first diode D1 of the diode 107 connected tothe negative terminal of the first and second inverters 103 and 104.

Therefore, the DC link capacitor Cdc in the voltage converter 105 isrecharged. At this time, the recharging controller 200 detects the phaseVs of the commercial electricity supplied to the first neutral point N1of the first motor 101 and the second neutral point N2 of the secondmotor 102, the voltage Vdc of the DC link capacitor Cdc which isrecharged, the battery voltage Vb, the voltage Vbc of the smoothingcapacitor Cbc connected to both ends of the battery 106, the inductorcurrent I_(L), and the charging current Ib at step S105, and determinesthe recharging mode based thereon at step S106.

Particularly, the recharging controller 200 determines whether therecharging mode is a current control mode where the battery voltage ismaintained to be higher than or equal to a predetermined referencevoltage (e.g., 80% of a maximum voltage) at step S107.

If the recharging mode is not the current control mode at the step S107,the recharging controller 200 decides a voltage control value which canmaintain the voltage Vbc of the smoothing capacitor Cbc connected toboth ends of the battery 106 to be constant at step S108.

Subsequently, the recharging controller 200 controls operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the voltage controlvalue decided at the step S108 and recharges the battery 106 at stepS109. Meanwhile, if the recharging mode is the current control mode atthe step S107, the recharging controller 200 decides a current controlvalue considering a detecting error at step S110.

Thereafter, the recharging controller 200 controls the operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the decided currentcontrol value, and controls a charging current of the battery 106 tofollow the current control value at step S111.

The recharging controller 200 determines whether the battery 106 iscompletely recharged at step S112. If the battery 106 is not completelyrecharged at step S112, the recharging controller 200 returns to stepS110 and repeats steps S110 to S112. If the battery 106 is completelyrecharged at step S112, the recharge of the battery 106 is finished atstep S113 in order for the battery 106 to be overcharged.

As described above. the exterior commercial electricity is supplied tothe first neutral point of the first motor and the second neutral pointof the second motor so as to recharge the DC link capacitor, and thebattery is stably recharged through a PWM control of the electricswitching element of the voltage converter according to the firstexemplary embodiment of the present invention. Since an expensiverecharging device is not used, it is possible to reduce manufacturingcosts while enhancing fuel economy.

Second Exemplary Embodiment

Hereinafter, a second exemplary embodiment of the present invention willbe described in detail referring to the drawings.

FIG. 5 is a circuit diagram of a recharging system of a hybrid vehicleaccording to the second exemplary embodiment of the present invention.

Referring to FIG. 5, the second exemplary embodiment of the presentinvention preferably includes at least a first motor 101, a second motor102, a first inverter 103, a second inverter 104, a voltage converter105, a battery 106, a diode 107 (for example, including first and seconddiodes D1 and D2), a recharging port 108, a connection detector 109, amain relay SR1 and SR2, and a recharging controller 200.

The first motor 101 is a 3-phase AC electric motor, which can beoperated as an electric motor to start an engine (not shown), andselectively operated as a generator driven by the engine.

The first motor 101 preferably is powered by 3-phase AC voltage suppliedthrough the first inverter 103 so as to start the engine. In addition,the first motor 101 can be driven by the engine so as to generate3-phase AC voltage and output the 3-phase AC voltage to the firstinverter 103.

The second motor 102 preferably is a 3-phase AC electric motor fordriving a driving wheel (not shown) and generating driving torque by3-phase AC voltage supplied from the second inverter 104.

In addition, the second motor 102 can be operated as a generator in acase of regenerative braking of the vehicle so as to generate 3-phase ACvoltage and output the 3-phase AC voltage to the second inverter 104.

The first motor 101 includes a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a firstneutral point N1 and the other end connected to a corresponding arm ofthe first inverter 103.

The first neutral point N1 of the first motor 101 is connected tocommercial electricity 300 that preferably is input from the exterior.

The second motor 102 includes a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a secondneutral point N2 and the other end connected to a corresponding arm ofthe second inverter 104.

The second neutral point N2 of the second motor 102 is connected tocommercial electricity 300 that preferably is input from the exterior.

The first inverter 103 converts the DC voltage of the battery 106supplied through the voltage converter 105 into the 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the first motor 101 as a drivingvoltage.

The first inverter 103 is connected to a DC link (a portion to which Vdcis applied) of the voltage converter 105 and the second diode D2 of thediode 107 so as to form a circulation path when the commercialelectricity 300 supplied to the first inverter 103 through the firstneutral point N1 of the first motor 101 has a positive value (Vs>0).

The second inverter 104 converts the DC voltage of the battery 106supplied through the voltage converter 105 into 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the second motor 102 as a drivingvoltage.

The second inverter 104 is connected to the DC link of the voltageconverter 105 and the first diode D1 of the diode 107 so as to form acirculation path when the commercial electricity 300 supplied to thesecond inverter 104 through the second neutral point N2 of the secondmotor 102 has a negative value (Vs<0).

The first inverter 103 is formed by connecting electric switchingelements in series, and includes U phase arms Sau and Sau′, V phase armsSay and Say′, and W phase arms Saw and Saw′. One of an NPN transistor,an IGBT (Insulated Gate Bipolar Transistor), and an MOSFET may be usedas the electric switching element.

The second inverter 104 is formed by connecting electric switchingelements in series, and includes U phase arms Sbu and Sbu′, V phase armsSbv and Sbv′, and W phase arms Sbw and Sbw′.

One of an NPN transistor, an IGBT (Insulated Gate Bipolar Transistor),and an MOSFET may be used as the electric switching element.

The voltage converter 105 preferably is a DC/DC converter, and thusraises or lowers the DC voltage supplied from the battery 106 to avoltage of a predetermined level according to a PWM duty control signalapplied from the recharging controller 200, and outputs it to the firstinverter 103 or the second inverter 104.

In addition, the voltage converter 105 preferably raises or lowers theDC voltage applied from the first inverter 103 or the second inverter104 according to a PWM duty control signal applied from the rechargingcontroller 200 and outputs it to the battery 106 as a rechargingvoltage.

The voltage converter 105 preferably is connected to both ends of thebattery 106, and includes first and second electric switching elementsS1 and S2 connected in series with a DC link capacitor Cdc and asmoothing capacitor Cbc smoothing a voltage change between both ends ofthe battery 106.

In a case that the exterior commercial electricity 300 supplied to thefirst neutral point N1 of the first motor 101 and the second neutralpoint N2 of the second motor 102 is supplied to the DC link forming thecirculation path through the first inverter 103 and the second inverter104, the voltage converter 105 switches on or off the first electricswitching element S1 and the second electric switching element S2according to a control signal applied from the recharging controller 200and recharges the battery 106.

The battery 106 preferably utilizes DC electricity. For example, one ofnickel-hydrogen and lithium-ion rechargeable battery and a capacitor oflarge capacity may be used as the battery 106. The DC voltage rechargedin the voltage converter 105 is raised or lowered so as to be suppliedto the first motor 101 or the second motor 102.

In addition, the battery 106 is recharged by the exterior commercialelectricity 300 which is raised or lowered by the voltage converter 105and is applied to the battery 106.

The diode 107 includes the first diode D1 and the second diode D2. Oneterminal, e.g., an anode terminal of the diode 107 is connected to anegative terminal of the first and second inverters 103 and 104, and acathode terminal is connected to the exterior commercial electricity 300and the first and second neutral points N1 and N2 of the first andsecond motors 101 and 102.

The recharging port 108 is connected to a recharging port 310 of theexterior commercial electricity 300, and receives electricity forrecharging the battery 106.

The connection detector 109 detects a connection of a connector forconnecting the commercial electricity 300 to the recharging port 108 andtransmits information corresponding thereto to the recharging controller200. The connection detector 109 may be a cover open detector whichdetects that a cover of the recharging port is open.

In addition, the connection of the commercial electricity 300 to therecharging port 108 may be detected by communication between therecharging port 108 and a recharging stand for supplying the commercialelectricity.

The communication between the recharging port 108 and the rechargingstand can be done by various means, for example, wire communication andwireless communication including common interfaces such as CANcommunication or Bluetooth communication.

The connection detector 109 transmits aim of recharging the battery 106to the recharging controller 200 before the commercial electricity 300is electrically connected to the first neutral point N1 of the firstmotor 101 and the second neutral point N2 of the second motor 102.

The main relay SR1 and SR2 is connected to both ends of the battery 106and controls voltage and current input to or output from the battery106. The commercial electricity 300 is selectively connected to thesystem through the recharging port 310.

The commercial electricity 300 may be AC electricity or DC electricity.

In a case that the connection signal of the connector or open of thecover of the recharging port is detected, the recharging controller 200recognizes this as the aim for recharging the battery 106. In this case,the recharging controller 200 performs the initial activation so as tostabilize the system before the exterior commercial electricity 300 issupplied.

If the initial activation of the recharging controller 200 is performed,the recharging controller 200 switches on the main relay SR1 and SR2 andpre-recharges the DC link capacitor Cdc to a voltage of predeterminedlevel with the battery 106. Subsequently, the recharging controller 200supplies the exterior commercial electricity 300 to the system.Therefore, it is possible to prevent occurrence of an inrush currentwhen the commercial electricity 300 is supplied, thus protectingelectric switching elements used in conjunction with the secondexemplary embodiment of the present invention.

If the exterior commercial electricity 300 is not supplied to the firstneutral point N1 of the first motor 101 and the second neutral point N2of the second motor 102 after the recharge of the battery 106 iscompleted or the connector (for example, a recharging stand) isdisconnected during recharging, the recharging controller 200 controlsthe first electric switching element S1 and the second electricswitching element S2 in the voltage converter 105 so as to supply aremaining voltage remaining in the DC link capacitor Cdc to the battery106 and to maintain the battery 106 to be a maximum recharge state.After the DC link capacitor Cdc is discharged to a voltage lower than areference voltage, the recharging controller 200 switches off the mainrelay SR1 and SR2 so as to stabilize the system.

In a state that the initial activation and the pre-recharge of the DClink capacitor are performed, the recharging controller 200 detects thephase Vs of the commercial electricity 300 supplied to the first neutralpoint N1 of the first motor 101 and the second neutral point N2 of thesecond motor 102, the voltage Vdc of the DC link capacitor Cdc forming acirculation loop, a battery voltage Vb, a voltage Vbc of the smoothingcapacitor Cbc connected to both ends of the battery 106, an inductorcurrent I_(L), and a charging current Ib and determines a rechargingmode.

In addition, the recharging controller 200 decides a recharging controlvalue according to the recharging mode, and recharges the battery 106 byswitching on or off the first electric switching element S1 and thesecond electric switching element S2 of the voltage converter 105through the PWM duty control.

One of ordinary skill in the art would understand that driving the firstmotor by the battery voltage and starting the engine, recharging thebattery by the voltage generated by the driving torque of the engine,driving the second motor by the battery voltage and running the vehicle,and recharging the battery through the regenerative braking as performedin conjunction with the second exemplary embodiment of the presentinvention are the same as those according to conventional arts, anddetailed descriptions thereof will be omitted.

According to the second exemplary embodiment of the present invention,if connection of commercial electricity to the recharging port isdetected, the recharging controller recognizes that the commercialelectricity should be used for recharging the battery, performs theinitial activation, and pre-recharges the DC link capacitor. Inaddition, the second exemplary embodiment of the present inventionrelates to recharge of the battery 106 by supplying the exteriorcommercial electricity to the first neutral point N1 of the first motor101 and the second neutral point N2 of the second motor 102 without theneed for additional recharging devices, as described in further detailherein.

FIG. 6 is a flowchart of a method for recharging a battery by using arecharging system according to the second exemplary embodiment of thepresent invention.

Referring to FIG. 6, in a state that the recharging controller 200 ofthe hybrid vehicle according to the second exemplary embodiment of thepresent invention stands by at step S201, the recharging controller 200determines from the connection detector 109 whether the exteriorcommercial electricity 300 is connected at step S202.

The connection of the exterior commercial electricity 300 may bedetected by the cover of the recharging port being open, a connectionsignal of the connector, or communication with the recharging stand.

If the connection of the exterior commercial electricity 300 is detectedat the step S202, the recharging controller 200 performs initialactivation thereof at step S203.

For reference, the recharging controller 200 of digital device needs aninitial activation time (for example, on the order of about tens of μsto hundreds of ms) so as to operate normally after electricity issupplied. In addition, if the recharging controller 200 is notactivated, the recharging controller 200 will not output a normalcontrol signal.

If high voltage is supplied to the first inverter 103, the secondinverter 104, and voltage converter 105 through the first neutral pointN1 of the first motor 101 and the second neutral point N2 of the secondmotor N2, a control electricity cannot be normally applied to a drivingportion of the electric switching element, e.g., a gate drive.Therefore, the electric switching elements may operate abnormally bynoise, overcurrent may be supplied, or components may be damaged.

If the exterior commercial electricity 300 is connected through theconnection of the recharging stand or the connector to the rechargingport 108 in a state that the initial activation of the rechargingcontroller 200 is performed, the commercial electricity 300 is suppliedto the first neutral point N1 of the first motor 101 and the secondneutral point N2 of the second motor 102 at step S204.

At step S205, an electricity loop shown in FIG. 3 is formed if the phaseof the commercial electricity 300 is a positive value (Vs>0), and theelectricity loop shown in FIG. 4 is formed if the phase of thecommercial electricity 300 is a negative value (Vs<0). Therefore, the DClink capacitor Cdc included in the voltage converter 105 is recharged.

The electricity loop formed according to the phase Vs of the commercialelectricity 300 is the same as that of the first exemplary embodiment ofthe present invention, and thus a detailed description thereof will beomitted.

At this time, the recharging controller 200 detects the phase Vs of thecommercial electricity supplied to the first neutral point N1 of thefirst motor 101 and the second neutral point N2 of the second motor 102,the voltage Vdc of the DC link capacitor Cdc which is recharged, thebattery voltage Vb, the voltage Vbc of the smoothing capacitor Cbcconnected to both ends of the battery 106, the inductor current I_(L),and the charging current Ib at step S206, and determines the rechargingmode based thereon at step S207.

Particularly, the recharging controller 200 determines whether therecharging mode is a voltage control mode where the battery voltage ismaintained to be lower than a predetermined reference voltage (e.g., 80%of a maximum voltage) at step S208.

If the recharging mode is the voltage control mode at the step S208, therecharging controller 200 decides a voltage control value which canmaintain the voltage Vbc of the smoothing capacitor Cbc connected toboth ends of the battery 106 to be constant at step S209.

Subsequently, the recharging controller 200 controls operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the voltage controlvalue decided at the step S209 and performs a high-speed recharge of thebattery 106 at step S210. If the recharging mode is not the voltagecontrol mode at the step S208, the recharging controller 200 determinedthat the recharging mode is a current control mode and decides a currentcontrol value considering a detecting error at step S211.

Thereafter, the recharging controller 200 controls the operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the decided currentcontrol value, and controls a charging current of the battery 106 tofollow the current control value at step S212.

The recharging controller 200 determines whether the battery 106 iscompletely recharged at step S213. If the battery 106 is not completelyrecharged at the step S213, the recharging controller 200 returns to thestep S211 and repeats the steps S211 to S213. If the battery 106 iscompletely recharged at the step S213, the recharge of the battery 106is finished at step S113 in order for the battery 106 to be overcharged.

Subsequently, the recharging controller 200 detects the connection ofthe exterior commercial electricity 300 at step S214, and determineswhether the exterior commercial electricity 300 is disconnected by thedisconnection of the connector (recharging stand) from the system atstep S215.

If the exterior commercial electricity 300 is disconnected at the stepS215, the recharging controller 200 controls the first electricswitching element S1 and the second electric switching element S2 in thevoltage converter 105 so as to supply the remaining voltage remaining inthe DC link capacitor Cdc to the battery 106 and to maintain the battery106 to be a maximum recharge state. That is, the DC link capacitor Cdcis discharged to a voltage lower than the reference voltage at stepS216.

Subsequently, the recharging controller 200 detects the voltage Vdc ofthe DC link capacitor Cdc and determines whether the voltage Vdc islower than the reference voltage at step S217. If the voltage Vdc of theDC link capacitor Cdc is greater than or equal to the reference voltageat the step S217, the recharging controller 200 returns to the stepS216. If the voltage Vdc of the DC link capacitor Cdc is lower than thereference voltage at the step S217, the recharging controller 200switches off the main battery SR1 and SR2 mounted between both ends ofthe battery 106 and controlling input or output voltage of the battery106 so as to stabilize the system at step S218. After that, therecharging controller completes the recharge of the battery 106 at stepS219.

It is described in this specification that the second exemplaryembodiment of the present invention is applied to a case in which thedisconnection of the connector (for example, a recharging stand) isdetected after the recharge is completed. However, the second exemplaryembodiment of the present invention also can be applied to a case inwhich the disconnection of the connector (recharging stand) connected tothe exterior commercial electricity 300 is detected during the battery106 is recharged. That is, in a case that the connector is disconnectedduring the battery is recharged, the recharging controller 200discharges the DC link capacitor Cdc to the voltage lower than thereference voltage.

FIG. 7 is a flowchart of a method for pre-recharging a DC link by usinga recharging system according to the second exemplary embodiment of thepresent invention.

Referring to FIG. 7, in a state that the recharging controller 200 ofthe hybrid vehicle according to the second exemplary embodiment of thepresent invention stands by at step S301, the recharging controller 200determines from the connection detector 109 whether the exteriorcommercial electricity 300 is connected at step S302.

The connection of the exterior commercial electricity 300 may bedetected by the cover of the recharging port being open, a connectionsignal of the connector, or the communication with the recharging stand.

If the connection of the exterior commercial electricity 300 is detectedat the step S302, the recharging controller 200 performs the initialactivation thereof at step S303.

Generally, if the battery 106 begins to be recharged by the supply ofthe exterior commercial electricity 300, commercial electricity 300 ofhigh voltage is supplied in a state that the voltage Vdc of DC linkcapacitor Cdc is maintained to be 0V. Therefore, a problem of inrushcurrent may occur.

Such inrush current can result in fatal damage to electric switchingelements constituting the first inverter 103, the second inverter 104,and the voltage converter 105.

Therefore, if the initial activation of the recharging controller 200 isperformed, the recharging controller 200 switches on the main relay SR1and SR2 and outputs the electricity of the battery 106 to the DC link atstep S304.

At this time, the recharging controller 200 controls the first electricswitching element S1 and the second electric switching element S2 in thevoltage converter 105 and pre-recharges the DC link capacitor Cdc atstep S305.

Subsequently, the recharging controller 200 determines whether the DClink capacitor Cdc is recharged to the voltage greater than or equal tothe predetermined voltage at step S306. If the voltage of the DC linkcapacitor Cdc does not reach to the predetermined voltage at the stepS306, the recharging controller 200 returns to the step S305 andpre-recharges the DC link capacitor Cdc.

On the contrary, if the DC link capacitor Cdc is recharged to thevoltage greater than or equal to the predetermined voltage at the stepS306, the recharging controller 200 performs the recharge of the battery106 by using the exterior commercial electricity 300 according to theflowchart shown in FIG. 6 at step S307.

As described above, if the connection of the exterior commercialelectricity is detected for recharging the battery, the rechargingcontroller performs the initial activation thereof so as to stabilizethe system and pre-recharges the DC link capacitor with the batteryvoltage so as to prevent occurrence of the inrush current according tothe second exemplary embodiment of the present invention.

In addition, exterior commercial electricity is supplied to the firstneutral point of the first motor and the second neutral point of thesecond motor so as to recharge the DC link capacitor, and the battery isstably recharged through a PWM control of the electric switching elementof the voltage converter according to the second exemplary embodiment ofthe present invention. Since an expensive recharging device is not used,it is possible to reduce manufacturing costs and enhance fuel economy.

If the disconnection of the connector or the recharging stand isdetected when the battery is recharged completely or during the batteryis recharged, the DC link capacitor can be discharged to the voltagelower than the reference voltage. Therefore, the system may bestabilized and the battery may maintain the maximum recharge state.

Third Exemplary Embodiment

Hereinafter, a third exemplary embodiment of the present invention willbe described in detail referring to the drawings.

FIG. 8 is a circuit diagram of a recharging system of a hybrid vehicleaccording to the third exemplary embodiment of the present invention.Referring to FIG. 8, the third exemplary embodiment of the presentinvention preferably includes at least a first motor 101, a second motor102, a first inverter 103, a second inverter 104, a voltage converter105, a battery 106, a diode 107 (for example, including first and seconddiodes D1 and D2), a recharging port 108, a connection detector 109, amain relay SR1 and SR2, an input terminal switch 110, and a rechargingcontroller 200.

The first motor 101 is a 3-phase AC electric motor, which can beoperated as an electric motor to start an engine (not shown), andselectively operated as a generator driven by the engine.

The first motor 101 preferably is powered by 3-phase AC voltage suppliedthrough the first inverter 103 so as to start the engine. In addition,the first motor 101 can be driven by the engine so as to generate3-phase AC voltage and outputs the 3-phase AC voltage to the firstinverter 103.

The second motor 102 preferably is a 3-phase AC electric motor fordriving a driving wheel (not shown) and generating driving torque by3-phase AC voltage supplied from the second inverter 104.

In addition, the second motor 102 can be operated as a generator in acase of regenerative braking of the vehicle so as to generate 3-phase ACvoltage and outputs the 3-phase AC voltage to the second inverter 104.

The first motor 101 includes a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a firstneutral point N1 and the other end connected to a corresponding arm ofthe first inverter 103.

The first neutral point N1 of the first motor 101 is connected tocommercial electricity 300 that preferably is input from the exterior.

The second motor 102 includes a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a secondneutral point N2 and the other end connected to a corresponding arm ofthe second inverter 104.

The second neutral point N2 of the second motor 102 is connected to thecommercial electricity 300 input from the exterior.

The first inverter 103 converts the DC voltage of the battery 106supplied through the voltage converter 105 into 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the first motor 101 as a drivingvoltage.

The first inverter 103 is connected to a DC link (a portion to which Vdcis applied) of the voltage converter 105 and the second diode D2 of thediode 107 so as to form a circulation path when the commercialelectricity 300 supplied to the first inverter 103 through the firstneutral point N1 of the first motor 101 has positive value (Vs>0).

The second inverter 104 converts the DC voltage of the battery 106supplied through the voltage converter 105 into 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the second motor 102 as a drivingvoltage.

The second inverter 104 is connected to the DC link of the voltageconverter 105 and the first diode D1 of the diode 107 so as to form acirculation path when the commercial electricity 300 supplied to thesecond inverter 104 through the second neutral point N2 of the secondmotor 102 has a negative value (Vs<0).

The first inverter 103 is formed by connecting electric switchingelements in series, and includes U phase arms Sau and Sau′, V phase armsSay and Say′, and W phase arms Saw and Saw′.

One of an NPN transistor, an IGBT (Insulated Gate Bipolar Transistor),and an MOSFET may be used as the electric switching element.

The second inverter 104 is formed by connecting electric switchingelements in series, and includes U phase arms Sbu and Sbu′, V phase armsSbv and Sbv′, and W phase arms Sbw and Sbw′.

One of an NPN transistor, an IGBT (Insulated Gate Bipolar Transistor),and an MOSFET may be used as the electric switching element.

The voltage converter 105 is a DC/DC converter, raises or lowers the DCvoltage supplied from the battery 106 to a voltage of predeterminedlevel according to a PWM duty control signal applied from the rechargingcontroller 200, and outputs it to the first inverter 103 or the secondinverter 104.

In addition, the voltage converter 105 raises or lowers the DC voltageapplied from the first inverter 103 or the second inverter 104 accordingto a PWM duty control signal applied from the recharging controller 200and outputs it to the battery 106 as a recharging voltage.

The voltage converter 105 preferably is connected to both ends of thebattery 106, and includes first and second electric switching elementsS1 and S2 connected in series with a DC link capacitor Cdc and asmoothing capacitor Cbc smoothing a voltage change between both ends ofthe battery 106.

In a case that the exterior commercial electricity 300 supplied to thefirst neutral point N1 of the first motor 101 and the second neutralpoint N2 of the second motor 102 is supplied to the DC link forming thecirculation path through the first inverter 103 and the second inverter104, the voltage converter 105 switches on or off the first electricswitching element S1 and the second electric switching element S2according to a control signal applied from the recharging controller 200and recharges the battery 106.

The battery 106 preferably utilizes DC electricity. For example, one ofnickel-hydrogen and lithium-ion rechargeable battery and a capacitor oflarge capacity may be used as the battery 106. The DC voltage rechargedin the voltage converter 105 is raised or lowered so as to be suppliedto the first motor 101 or the second motor 102.

In addition, the battery 106 is recharged by the exterior commercialelectricity 300 which is raised or lowered by the voltage converter 105and is applied to the battery 106.

The diode 107 includes the first diode D1 and the second diode D2. Oneterminal, e.g., an anode terminal of the diode 107 is connected to anegative terminal of the first and second inverters 103 and 104, and acathode terminal is connected to the exterior commercial electricity 300and the first and second neutral points N1 and N2 of the first andsecond motors 101 and 102.

The recharging port 108 is connected to a recharging port 310 of theexterior commercial electricity 300, and receives electricity forrecharging the battery 106.

The connection detector 109 detects a connection of a connector forconnecting the commercial electricity 300 to the recharging port 108 andtransmits information corresponding thereto to the recharging controller200.

The connection detector 109 may be a cover open detector which detectsthat a cover of the recharging port is open.

In addition, the connection of the commercial electricity 300 to therecharging port 108 may be detected by communication between therecharging port 108 and a recharging stand for supplying the commercialelectricity.

The communication between the recharging port 108 and the rechargingstand can be done by various means, for example, wire communication andwireless communication including common interfaces such as CANcommunication or Bluetooth communication.

The connection detector 109 transmits aim of recharging the battery 106to the recharging controller 200 before the commercial electricity 300is electrically connected to the first neutral point N1 of the firstmotor 101 and the second neutral point N2 of the second motor 102.

The main relay SR1 and SR2 is connected to both ends of the battery 106and controls voltage and current input to or output from the battery106.

The input terminal switch 110 controls supply of the exterior commercialelectricity 300 to the first neutral point N1 of the first motor 101 andthe second neutral point N2 of the second motor 102 through therecharging port 108.

The input terminal switch 110 includes a first relay SR3 connected tothe first diode D1 and the first neutral point N1 of the first motor 101and a second relay SR4 connected to the second diode D2 and the secondneutral point N2 of the second motor 102.

The input terminal switch 110 switches on or off by the control of therecharging controller 200. Therefore, the input terminal switch 110prevents the exterior commercial electricity 300 from being supplied inthe system and stabilizes the system until the recharging controller 200performs the initial activation and pre-recharges the DC link capacitorCdc to be greater than or equal to the predetermined voltage by usingthe battery voltage when the connection of the exterior commercialelectricity 300 is detected.

The commercial electricity 300 is selectively connected to the systemthrough the recharging port 310. The commercial electricity 300 may beAC electricity or DC electricity.

In a case that the connection signal of the connector or open of thecover of the recharging port is detected, the recharging controller 200recognizes this as the aim for recharging the battery 106 and performsthe initial activation so as to stabilize the system before the exteriorcommercial electricity 300 is supplied.

If the initial activation of the recharging controller 200 is performed,the recharging controller 200 switches on the main relay SR1 and SR2 andpre-recharges the DC link capacitor Cdc to a voltage of predeterminedlevel with the battery 106. Subsequently, the recharging controller 200supplies the exterior commercial electricity 300 to the system.Therefore, it is possible to prevent occurrence of an inrush currentwhen the commercial electricity 300 is supplied, thus protectingelectric switching elements used in conjunction with the third exemplaryembodiment of the present invention.

If the exterior commercial electricity 300 is not supplied to the firstneutral point N1 of the first motor 101 and the second neutral point N2of the second motor 102 after the recharge of the battery 106 iscompleted or the connector (for example, a recharging stand) isdisconnected during recharging, the recharging controller 200 controlsthe first electric switching element S1 and the second electricswitching element S2 in the voltage converter 105 so as to supply aremaining voltage remaining in the DC link capacitor Cdc to the battery106 and to maintain the battery 106 to be a maximum recharge state.After the DC link capacitor Cdc is discharged to a voltage lower than areference voltage, the recharging controller 200 switches off the mainrelay SR1 and SR2 so as to stabilizes the system.

In a state that the initial activation and the pre-recharge of the DClink capacitor are performed, the recharging controller 200 switches onthe input terminal switch 110 so as for the exterior commercialelectricity 300 to be supplied to the first neutral point N1 of thefirst motor 101 and the second neutral point N2 of the second motor 102.

In addition, the recharging controller 200 detects the phase Vs of thecommercial electricity 300 supplied to the first neutral point N1 of thefirst motor 101 and the second neutral point N2 of the second motor 102,the voltage Vdc of the DC link capacitor Cdc forming a circulation loop,a battery voltage Vb, a voltage Vbc of the smoothing capacitor Cbcconnected to both ends of the battery 106, an inductor current I_(L),and a charging current Ib and determines a recharging mode.

In addition, the recharging controller 200 decides a recharging controlvalue according to the recharging mode, and recharges the battery 106 byswitching on or off the first electric switching element S1 and thesecond electric switching element S2 of the voltage converter 105through the PWM duty control.

One of ordinary skill in the art would understand that driving the firstmotor by the battery voltage and starting the engine, recharging thebattery by the voltage generated by the driving torque of the engine,driving the second motor by the battery voltage and running the vehicle,and recharging the battery through the regenerative braking as performedin conjunction with the third exemplary embodiment of the presentinvention are the same as those according to conventional arts, anddetailed descriptions thereof will be omitted.

According to the third exemplary embodiment of the present invention, ifrecharging of the battery is detected, the recharging controllerperforms the initial activation and pre-recharges the DC link capacitorin a state that the input terminal switch is switched off and thecommercial electricity is not supplied in the system. In addition, thethird exemplary embodiment of the present invention relates to therecharge of the battery 106 by switching on the input terminal switchand supplying the exterior commercial electricity to the first neutralpoint N1 of the first motor 101 and the second neutral point N2 of thesecond motor 102 if the DC link capacitor is pre-recharged, and will bedescribed in further detail.

FIG. 9 is a flowchart of a method for pre-recharging a DC link by usinga recharging system according to the third exemplary embodiment of thepresent invention.

Referring to FIG. 9, in a state that the recharging controller 200 ofthe hybrid vehicle according to the third exemplary embodiment of thepresent invention stands by at step S401, the recharging controller 200analyzes a signal of the connection detector 109 and determines whetherthe exterior commercial electricity 300 for recharging the battery 106is connected to the recharging port 108 at step S402.

The connection of the exterior commercial electricity 300 may bedetected by the cover of the recharging port being open, a connectionsignal of the connector, or communication with the recharging stand.

If the connection of the exterior commercial electricity 300 is detectedat the step S402, the recharging controller 200 maintains the inputterminal switch 110 in switching-off state and performs initialactivation thereof at step S403.

In addition, the recharging controller 200 switches on the main relaySR1 and SR2 so as to supply the battery voltage to the voltage converter105 at step S404, and operates the first electric switching element S1and the second electric switching element S2 in the voltage converter105 at step S405 such that the battery voltage is supplied to the DClink capacitor Cdc and the DC link capacitor Cdc is pre-recharged.

After that, the recharging controller 200 detects a recharging voltageof the DC link capacitor Cdc which is recharged, and determines therecharging voltage is higher than or equal to the predetermined voltageat step S406.

If the DC link capacitor Cdc is pre-recharged to the voltage higher thanor equal to the predetermined voltage at the step S406, the rechargingcontroller 200 switches on the input terminal switch 110 which wasswitching-off state at step S407 and supplies the exterior commercialelectricity 300 connected to the recharging port 108 to the firstneutral point N1 of the first motor 101 and the second neutral point N2of the second motor 102 at step S408.

At this time, the electricity loop passing through the first neutralpoint N1 of the first motor 101, the second neutral point N2 of thesecond motor 102, the first inverter 103, the second inverter 104, theDC link capacitor Cdc, and the first diode D1 and the second diode D2 inthe diode 107 is formed according to the phase Vs of the commercialelectricity 300.

Therefore, the DC link capacitor Cdc in the voltage converter 105 isrecharged, and the recharging controller 200 controls the first electricswitching element S1 and the second electric switching element S2 in thevoltage converter 105 so as to recharge the battery 106 at step S409.

The electricity loop formed according to the phase Vs of the commercialelectricity 300 is the same as that of the first exemplary embodiment ofthe present invention, and thus, a detailed description thereof will beomitted.

FIG. 10 is a flowchart of a method for recharging a battery by using arecharging system according to the third exemplary embodiment of thepresent invention.

As described above, if the input terminal switch 110 is switched on andthe exterior commercial electricity 300 is supplied to the first neutralpoint N1 of the first motor 101 and the second neutral point N2 of thesecond motor 102 at step S501, the electricity loop shown in FIG. 3 andFIG. 4 is formed according to the phase Vs of the commercial electricity300 at step S502.

The recharging controller 200 detects the phase Vs of the commercialelectricity supplied to the first neutral point N1 of the first motor101 and the second neutral point N2 of the second motor 102, the voltageVdc of the DC link capacitor Cdc which is recharged, the battery voltageVb, the voltage Vbc of the smoothing capacitor Cbc connected to bothends of the battery 106, the inductor current I_(L), and the chargingcurrent Ib at step S503, and determines the recharging mode basedthereon at step S504.

Particularly, the recharging controller 200 determines whether therecharging mode is a current control mode where the battery voltage ismaintained to be higher than or equal to a predetermined referencevoltage (e.g., 80% of a maximum voltage) at step S505.

If the recharging mode is not the current control mode at the step S505,the recharging controller 200 decides that the recharging mode is thevoltage control mode and decides a voltage control value which canmaintain the voltage Vbc of the smoothing capacitor Cbc connected toboth ends of the battery 106 to be constant at step S506.

Subsequently, the recharging controller 200 controls operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the voltage controlvalue decided at the step S506 and performs a high-speed recharge of thebattery 106 at step S507.

If the recharging mode is the current control mode at the step S505, therecharging controller 200 decides a current control value considering adetecting error at step S508.

Thereafter, the recharging controller 200 controls the operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the decided currentcontrol value, and controls a charging current of the battery 106 tofollow the current control value at step S509.

The recharging controller 200 determines whether the battery 106 iscompletely recharged at step S510. If the battery 106 is not completelyrecharged at the step S510, the recharging controller 200 returns to thestep S508 and repeats the steps S508 to S510. If the battery 106 iscompletely recharged at the step S510, the recharge of the battery 106is finished at step S511 in order for the battery 106 to be overcharged.

FIG. 11 is a flowchart of a method for completing a recharge of abattery by using a recharging system according to the third exemplaryembodiment of the present invention.

The recharging controller 200 determines whether the battery 106 isrecharged completely or the recharging connector (recharging stand) isdisconnected from the system at step S601.

If the battery 106 is recharged completely or the recharging connector(recharging stand) is disconnected from the system at the step S601, therecharging controller 200 switches off the input terminal switch 110 anddisconnects the first neutral point N1 of the first motor 101 and thesecond neutral point N2 of the second motor 102 from the recharging port108 at step S602.

Subsequently, the recharging controller 200 controls the first electricswitching element S1 and the second electric switching element S2 in thevoltage converter 105 so as to supply the remaining voltage remaining inthe DC link capacitor Cdc to the battery 106 and to maintain the battery106 to be a maximum recharge state. That is, the DC link capacitor Cdcis discharged to a voltage lower than the reference voltage at stepS603.

The recharging controller 200 detects the voltage Vdc of the DC linkcapacitor Cdc at step S604 and determines whether the voltage Vdc of theDC link capacitor Cdc is lower than the reference voltage at step S605.

If the voltage Vdc of the DC link capacitor Cdc is higher than or equalto the reference voltage at the step the S605, the recharging controller200 returns to the step S603 and discharges the DC link capacitor Cdc.

If the voltage Vdc of the DC link capacitor Cdc is lower than thereference voltage at the step S605, the recharging controller 200switches off the main battery SR1 and SR2 mounted between both ends ofthe battery 106 and controlling input or output voltage of the battery106 so as to stabilize the system at step S218. After that, therecharging controller completes the recharge of the battery 106 at stepS606.

As described above, if the connection of exterior commercial electricityis detected for recharging the battery, the recharging controllerperforms the initial activation thereof so as to stabilize the systemand pre-recharges the DC link capacitor with the battery voltage so asto prevent occurrence of the inrush current by controlling the inputterminal switch according to the third exemplary embodiment of thepresent invention.

Fourth Exemplary Embodiment

Hereinafter, a fourth exemplary embodiment of the present invention willbe described in detail referring to the drawings.

FIG. 12 is a circuit diagram of a recharging system of a hybrid vehicleaccording to the fourth exemplary embodiment of the present invention.

Referring to FIG. 12, the fourth exemplary embodiment of the presentinvention preferably includes at least a first motor 101, a second motor102, a first inverter 103, a second inverter 104, a voltage converter105, a battery 106, a diode 107 (for example, including first and seconddiodes D1 and D2), a recharging port 108, a connection detector 109, amain relay SR1 and SR2, an input terminal switch 110, and a rechargingcontroller 200.

The first motor 101 is a 3-phase AC electric motor, which can beoperated as an electric motor to start an engine (not shown), and isselectively operated as a generator driven by the engine.

The first motor 101 preferably is powered by 3-phase AC voltage suppliedthrough the first inverter 103 so as to start the engine. In addition,the first motor 101 can be driven by the engine so as to generate3-phase AC voltage and outputs the 3-phase AC voltage to the firstinverter 103.

The second motor 102 preferably is a 3-phase AC electric motor fordriving a driving wheel (not shown) and generating driving torque by3-phase AC voltage supplied from the second inverter 104.

In addition, the second motor 102 can be operated as a generator in acase of regenerative braking of the vehicle so as to generate 3-phase ACvoltage and outputs the 3-phase AC voltage to the second inverter 104.

The first motor 101 includes a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a firstneutral point N1 and the other end connected to a corresponding arm ofthe first inverter 103.

The first neutral point N1 of the first motor 101 is connected tocommercial electricity 300 that preferably is input from the exterior.

The second motor 102 includes a Y-type wiring 3-phase coil as a statorcoil. Also, U, V, and W phase coils forming the 3-phase coil each arerespectively provided with one end interconnected so as to form a secondneutral point N2 and the other end connected to a corresponding arm ofthe second inverter 104.

The second neutral point N2 of the second motor 102 is connected tocommercial electricity 300 that preferably is input from the exterior.

The first inverter 103 converts the DC voltage of the battery 106supplied through the voltage converter 105 into the 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the first motor 101 as a drivingvoltage.

The first inverter 103 is connected to a DC link (a portion to which Vdcis applied) of the voltage converter 105 and the second diode D2 of thediode 107 so as to form a circulation path when the commercialelectricity 300 supplied to the first inverter 103 through the firstneutral point N1 of the first motor 101 has a positive value (Vs>0).

The second inverter 104 converts the DC voltage of the battery 106supplied through the voltage converter 105 into the 3-phase AC voltageaccording to a PWM signal applied from the recharging controller 200 andsupplies the 3-phase AC voltage to the second motor 102 as a drivingvoltage.

The second inverter 104 is connected to the DC link of the voltageconverter 105 and the first diode D1 of the diode 107 so as to form acirculation path when the commercial electricity 300 supplied to thesecond inverter 104 through the second neutral point N2 of the secondmotor 102 has a negative value (Vs<0).

The first inverter 103 is formed by connecting electric switchingelements in series, and includes U phase arms Sau and Sau′, V phase armsSav and Sav′, and W phase arms Saw and Saw′. One of an NPN transistor,an IGBT (Insulated Gate Bipolar Transistor), and an MOSFET may be usedas the electric switching element.

The second inverter 104 is formed by connecting electric switchingelements in series, and includes U phase arms Sbu and Sbu′, V phase armsSbv and Sbv′, and W phase arms Sbw and Sbw′. One of an NPN transistor,an IGBT (Insulated Gate Bipolar Transistor), and an MOSFET may be usedas the electric switching element.

The voltage converter 105 preferably is a DC/DC converter, and thusraises or lowers the DC voltage supplied from the battery 106 to avoltage of predetermined level according to a PWM duty control signalapplied from the recharging controller 200, and outputs it to the firstinverter 103 or the second inverter 104.

In addition, the voltage converter 105 raises or lowers the DC voltageapplied from the first inverter 103 or the second inverter 104 accordingto a PWM duty control signal applied from the recharging controller 200and outputs it to the battery 106 as a recharging voltage.

The voltage converter 105 preferably is connected to both ends of thebattery 106, and includes first and second electric switching elementsS1 and S2 connected in series with a DC link capacitor Cdc and asmoothing capacitor Cbc smoothing a voltage change between both ends ofthe battery 106.

In a case that the exterior commercial electricity 300 supplied to thefirst neutral point N1 of the first motor 101 and the second neutralpoint N2 of the second motor 102 is supplied to the DC link forming thecirculation path through the first inverter 103 and the second inverter104, the voltage converter 105 switches on or off the first electricswitching element S1 and the second electric switching element S2according to a control signal applied from the recharging controller 200and recharges the battery 106.

The battery 106 preferably utilizes DC electricity. For example, one ofnickel-hydrogen and lithium-ion rechargeable battery and a capacitor oflarge capacity may be used as the battery 106. The DC voltage rechargedin the voltage converter 105 is raised or lowered so as to be suppliedto the first motor 101 or the second motor 102.

In addition, the battery 106 is recharged by the exterior commercialelectricity 300 which is raised or lowered by the voltage converter 105and is applied to the battery 106.

The diode 107 includes the first diode D1 and the second diode D2. Oneterminal, e.g., an anode terminal of the diode 107 is connected to anegative terminal of the first and second inverters 103 and 104, and acathode terminal is connected to the exterior commercial electricity 300and the first and second neutral points N1 and N2 of the first andsecond motors 101 and 102.

The recharging port 108 is connected to a recharging port 310 of theexterior commercial electricity 300, and receives electricity forrecharging the battery 106.

The connection detector 109 detects a connection of a connector forconnecting the commercial electricity 300 to the recharging port 108 andtransmits information corresponding thereto to the recharging controller200.

The connection detector 109 may be a cover open detector which detectsthat a cover of the recharging port is open.

In addition, the connection of the commercial electricity 300 to therecharging port 108 may be detected by communication between therecharging port 108 and a recharging stand for supplying the commercialelectricity.

The communication between the recharging port 108 and the rechargingstand can be done by various means, for example, wire communication andwireless communication including common interfaces such as CANcommunication or Bluetooth communication.

The connection detector 109 transmits aim of recharging the battery 106to the recharging controller 200 before the commercial electricity 300is electrically connected to the first neutral point N1 of the firstmotor 101 and the second neutral point N2 of the second motor 102.

The main relay SR1 and SR2 is connected to both ends of the battery 106and controls voltage and current input to or output from the battery106.

The input terminal switch 110 controls supply of the exterior commercialelectricity 300 to the first neutral point N1 of the first motor 101 andthe second neutral point N2 of the second motor 102 through therecharging port 108.

The input terminal switch 110 includes a first relay SR3 connected tothe first diode D1 and the first neutral point N1 of the first motor101, a second relay SR4 connected to the second diode D2 and the secondneutral point N2 of the second motor 102, and a third relay SR5connected in parallel with the first relay SR3 and connected in serieswith a resistance R1.

In addition, the input terminal switch 110 further includes a fourthrelay (not shown) connected in parallel with the second relay SR4 andconnected in series with a resistance (not shown).

The input terminal switch 110 switches on or off by the control of therecharging controller 200. Therefore, the input terminal switch 110makes the exterior commercial electricity 300 to be a low voltage stateby switching on the third relay SR5 connected in series with theresistance R1 and the second relay SR4 by the control of the rechargingcontroller 200 in a state that the connection of the exterior commercialelectricity 300 is detected. Subsequently, the input terminal switch 110supplies the commercial electricity 300 of the low voltage state to theDC link capacitor Cdc and pre-recharges the DC link capacitor Cdc. Ifthe DC link capacitor Cdc is pre-charged to the voltage higher than orequal to the predetermined voltage, the input terminal switch 110switches off the third relay SR5 and switches on the first relay SR3 andthe second relay SR4 so as to recharge the battery 106 by the supply ofthe normal commercial electricity 300.

The commercial electricity 300 is selectively connected to the systemthrough the recharging port 310. The commercial electricity 300 may beAC electricity or DC electricity.

In a case that the connection signal of the connector or open of thecover of the recharging port is detected, the recharging controller 200recognizes this as the aim for recharging the battery 106, switches offthe input terminal switch 110, and performs the initial activation so asto stabilize the system.

If the initial activation of the recharging controller 200 is performed,the recharging controller 200 switches on the third relay SR5 connectedin series with the resistance R1 and the second relay SR4 in the inputterminal switch 110 so as to make the commercial electricity 300 to bethe low voltage state, and supplies the commercial electricity 300 ofthe low voltage state to the DC link capacitor Cdc. Therefore, the DClink capacitor Cdc is pre-recharged. In addition, if the DC linkcapacitor Cdc is pre-recharged to the voltage higher than or equal tothe predetermined voltage, the recharging controller 200 switches offthe third relay SR5 and switches on the first relay SR3 and the secondrelay SR4 so as to recharge the battery by supplying the normalcommercial electricity 300.

If the exterior commercial electricity 300 is not supplied to the firstneutral point N1 of the first motor 101 and the second neutral point N2of the second motor 102 after the recharge of the battery 106 iscompleted or the connector (recharging stand) is disconnected duringrecharging, the recharging controller 200 controls the first electricswitching element S1 and the second electric switching element S2 in thevoltage converter 105 so as to supply a remaining voltage remaining inthe DC link capacitor Cdc to the battery 106 and to maintain the battery106 to be a maximum recharge state. After the DC link capacitor Cdc isdischarged to a voltage lower than a reference voltage, the rechargingcontroller 200 switches off the main relay SR1 and SR2 so as tostabilizes the system.

One of ordinary skill in the art would understand that driving the firstmotor by the battery voltage and starting the engine, recharging thebattery by the voltage generated by the driving torque of the engine,driving the second motor by the battery voltage and running the vehicle,and recharging the battery through the regenerative braking as performedin conjunction with the fourth exemplary embodiment of the presentinvention are the same as those according to conventional arts, anddetailed descriptions thereof will be omitted.

The fourth exemplary embodiment of the present invention relates to amethod for pre-recharging the DC link capacitor by supplying a lowvoltage when the commercial electricity is connected and for rechargingthe battery 106 by supplying normal commercial electricity to the firstneutral point N1 of the first motor 101 and the second neutral point N2of the second motor 102 when the DC link capacitor is pre-recharged, andwill be described in further detail.

FIG. 13 is a flowchart of a method for pre-recharging a DC link by usinga recharging system according to the fourth exemplary embodiment of thepresent invention.

Referring to FIG. 13, in a state that the recharging controller 200 ofthe hybrid vehicle according to the fourth exemplary embodiment of thepresent invention stands by at step S701, the recharging controller 200analyzes a signal of the connection detector 109 and determines whetherthe exterior commercial electricity 300 for recharging the battery 106is connected to the recharging port 108 at step S702.

The connection of the exterior commercial electricity 300 may bedetected by the cover of the recharging port being open, a connectionsignal of the connector, or the communication with the recharging stand.

If the connection of the exterior commercial electricity 300 is detectedat the step S702, the recharging controller 200 maintains the inputterminal switch 110 in switching-off state and performs the initialactivation thereof at step S703.

Subsequently, the recharging controller 200 maintains the main relay SR1and SR2 in switching-off state at step S704 and switches on the secondrelay SR4 and the third relay SR5 connected in series with theresistance R1 and connected in parallel with the first relay SR3 in theinput terminal switch 110 so as to make the commercial electricity 300to be the low voltage state through the resistance R1 at step S705.Thereafter, the recharging controller 200 supplies the commercialelectricity 300 of the low voltage state to the DC link capacitor Cdcand pre-recharges the DC link capacitor Cdc at step S706.

The recharging controller 200 detects a recharging voltage of the DClink capacitor Cdc which is recharged, and determines the rechargingvoltage is higher than or equal to the predetermined voltage at stepS707.

If the DC link capacitor Cdc is pre-recharged to the voltage higher thanor equal to the predetermined voltage at the step S707, the rechargingcontroller 200 switches off the third relay SR5 in the input terminalswitch 110 and switches on the first relay SR3 and the second relay SR4.Therefore, the commercial electricity 300 connected to the rechargingport 108 is supplied normally to the first neutral point N1 of the firstmotor 101 and the second neutral point N2 of the second motor 102 atstep S708.

Therefore, the electricity loop passing through the first neutral pointN1 of the first motor 101, the second neutral point N2 of the secondmotor 102, the first inverter 103, the second inverter 104, the DC linkcapacitor Cdc, and the first diode D1 and the second diode D2 in thediode 107 is formed according to the phase Vs of the commercialelectricity 300.

The DC link capacitor Cdc in the voltage converter 105 is recharged, andthe recharging controller 200 switches on the main relay SR1 and SR2 andcontrols the first electric switching element S1 and the second electricswitching element S2 in the voltage converter 105 so as to recharge thebattery 106 at step S710.

The electricity loop formed according to the phase Vs of the commercialelectricity 300 is the same as that of the first exemplary embodiment ofthe present invention, and thus, a detailed description thereof will beomitted.

FIG. 14 is a flowchart of a method for recharging a battery by using arecharging system according to the fourth exemplary embodiment of thepresent invention.

As described above, if the input terminal switch 110 is switched on andthe exterior commercial electricity 300 is supplied to the first neutralpoint N1 of the first motor 101 and the second neutral point N2 of thesecond motor 102 at step S801, the electricity loop shown in FIG. 3 andFIG. 4 is formed according to the phase Vs of the commercial electricity300 at step S802.

The recharging controller 200 detects the phase Vs of the commercialelectricity supplied to the first neutral point N1 of the first motor101 and the second neutral point N2 of the second motor 102, the voltageVdc of the DC link capacitor Cdc which is recharged, the battery voltageVb, the voltage Vbc of the smoothing capacitor Cbc connected to bothends of the battery 106, the inductor current I_(L), and the chargingcurrent Ib at step S803, and determines the recharging mode basedthereon at step S804.

Particularly, the recharging controller 200 determines whether therecharging mode is a current control mode where the battery voltage ismaintained to be higher than or equal to a predetermined referencevoltage (e.g., 80% of a maximum voltage) at step S805.

If the recharging mode is not the current control mode at the step S805,the recharging controller 200 decides that the recharging mode is thevoltage control mode and decides a voltage control value which canmaintain the voltage Vbc of the smoothing capacitor Cbc connected toboth ends of the battery 106 to be constant at step S806.

Subsequently, the recharging controller 200 controls operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the voltage controlvalue decided at the step S806 and performs a high-speed recharge of thebattery 106 at step S807.

If the recharging mode is the current control mode at the step S805, therecharging controller 200 decides a current control value considering adetecting error at step S808.

Thereafter, the recharging controller 200 controls the operations of thefirst electric switching element S1 and the second electric switchingelement S2 in the voltage converter 105 based on the decided currentcontrol value, and controls a charging current of the battery 106 tofollow the current control value at step S809.

The recharging controller 200 determines whether the battery 106 iscompletely recharged at step S810. If the battery 106 is not completelyrecharged at the step S810, the recharging controller 200 returns to thestep S808 and repeats the steps S808 to S810. If the battery 106 iscompletely recharged at the step S810, the recharge of the battery 106is finished at step S811 in order for the battery 106 to be overcharged.

FIG. 15 is a flowchart of a method for completing a recharge of abattery by using a recharging system according to the fourth exemplaryembodiment of the present invention.

The recharging controller 200 determines whether the battery 106 isrecharged completely or the recharging connector (recharging stand) isdisconnected from the system at step S901.

If the battery 106 is recharged completely or the recharging connector(recharging stand) is disconnected from the system at the step S901, therecharging controller 200 switches off the input terminal switch 110 anddisconnects the first neutral point N1 of the first motor 101 and thesecond neutral point N2 of the second motor 102 from the recharging port108 at step S902.

Subsequently, the recharging controller 200 controls the first electricswitching element S1 and the second electric switching element S2 in thevoltage converter 105 so as to supply the remaining voltage remaining inthe DC link capacitor Cdc to the battery 106 and to maintain the battery106 to be a maximum recharge state. That is, the DC link capacitor Cdcis discharged to a voltage lower than the reference voltage at stepS903.

The recharging controller 200 detects the voltage Vdc of the DC linkcapacitor Cdc at step S904 and determines whether the voltage Vdc of theDC link capacitor Cdc is lower than the reference voltage at step S905.

If the voltage Vdc of the DC link capacitor Cdc is higher than or equalto the reference voltage at the step the S905, the recharging controller200 returns to the step S903 and discharges the DC link capacitor Cdc.

If the voltage Vdc of the DC link capacitor Cdc is lower than thereference voltage at the step S905, the recharging controller 200switches off the main battery SR1 and SR2 mounted between both ends ofthe battery 106 and controlling input or output voltage of the battery106 so as to stabilize the system at step S218. Thereafter, therecharging controller completes the recharge of the battery 106 at stepS906.

As described above, if the connection of the exterior commercialelectricity is detected for recharging the battery, the rechargingcontroller performs the initial activation thereof so as to stabilizethe system and pre-recharges the DC link capacitor with the batteryvoltage so as to prevent occurrence of the inrush current by controllingthe input terminal switch according to the fourth exemplary embodimentof the present invention.

According to the present invention, since the battery is recharged by amotor and an inverter provided in a hybrid vehicle, an expensive chargercannot be used and price competitiveness may be enhanced.

Since weight of the hybrid vehicle is reduced, fuel economy may beenhanced. In addition, space availability may be enhanced.

Since the present invention provides high-speed recharging function byusing the motor of large capacity and the inverter provided in thehybrid vehicle, additional components and exterior chargers forhigh-speed recharge may not be needed.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A recharging system of a hybrid vehicle,comprising: a battery in which DC voltage is stored or for outputtingthe DC voltage; first and second motors configured to function as anelectric motor or a generator; first and second inverters for operatingthe first and second motors respectively; a voltage converter forraising or lowering the DC voltage of the battery such that the raisedor lowered DC voltage is supplied to the first and second inverters, inorder to raise or lower the DC voltage supplied from the first andsecond inverters such that the raised or lowered DC voltage is suppliedto the battery, and provided with a DC link; first and second diodeseach provided with an anode terminal connected to a negative terminal ofthe first and second inverters, and a cathode terminal connected to asource of commercial electricity and also connected to first and secondneutral points of the first and second motors; a recharging controllerfor carrying out a recharging mode by detecting at least one of a phaseof the commercial electricity supplied to the first and second neutralpoints of the first and second motors, a voltage of a DC link capacitorconnecting the voltage converter and the first and second inverters, abattery voltage, a voltage of a smoothing capacitor connected at bothterminals of the battery, a battery current, and a current flowing fromthe voltage converter to the battery, and controlling the voltageconverter through a PWM duty according to the recharging mode of thebattery such that the voltage of the DC link capacitor is raised orlowered, and is supplied to the battery; a main relay selectivelyconnecting the battery with the voltage converter; a recharging portselectively connecting the commercial electricity disposed at anexterior of the vehicle to the first and second diodes; a connectiondetector for detecting a connection of the commercial electricity; andan input terminal switch mounted between the recharging port and thefirst and second motors and selectively connecting the commercialelectricity to the first and second neutral points of the first andsecond motors by control of the recharging controller, wherein the inputterminal switch comprises a first relay connected to the first diode andthe first neutral point of the first motor; and a second relay connectedto the second diode and the second neutral point of the second motor. 2.The recharging system of claim 1, wherein the recharging controllerperforms an initial activation thereof, switches on the main relay, andswitches off the input terminal switch so as to pre-recharge the DC linkby means of the battery voltage in a case that the connection detectordetects the connection of the commercial electricity.
 3. The rechargingsystem of claim 2, wherein the recharging controller switches on theinput terminal switch and controls a recharge of the battery accordingto the recharging mode in a case that the pre-recharge of the DC link iscompleted.
 4. The recharging system of claim 3, wherein the rechargingcontroller decides the current control value and controls the chargingcurrent of the battery to follow the current control value in a casethat the recharging mode of the battery is the current control mode. 5.The recharging system of claim 3, wherein the recharging controllerdecides a voltage control value required for maintaining the voltage ofthe smoothing capacitor to be constant and controls the voltageconverter based on the voltage control value so as to recharge thebattery in a case that the recharging mode of the battery is not thecurrent control mode.